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Publication numberEP0592691 A1
Publication typeApplication
Application numberEP19930911954
PCT numberPCT/JP1993/000571
Publication dateApr 20, 1994
Filing dateApr 28, 1993
Priority dateApr 30, 1992
Also published asEP0592691A4
Publication number1993911954, 93911954, 93911954.1, EP 0592691 A1, EP 0592691A1, EP-A1-0592691, EP0592691 A1, EP0592691A1, EP19930911954, EP93911954, PCT/1993/571, PCT/JP/1993/000571, PCT/JP/1993/00571, PCT/JP/93/000571, PCT/JP/93/00571, PCT/JP1993/000571, PCT/JP1993/00571, PCT/JP1993000571, PCT/JP199300571, PCT/JP93/000571, PCT/JP93/00571, PCT/JP93000571, PCT/JP9300571
InventorsMamoru Uchiyama Manufacturing Corp Ohmori, Takashi Uchiyama Manufacturing Corp Namba, Tsukasa Uchiyama Manufacturing Corp Horichi, Masayasu Daikin Industries Ltd. Tomoda, Tsuyoshi Daikin Industries Ltd. Noguchi, Kazuhisa Daikin Industriesltd. Matsumoto, Etsuo Daikin Industries Ltd. Minamino
ApplicantDaikin Industries, Limited, Uchiyama Manufacturing Corp.
Export CitationBiBTeX, EndNote, RefMan
External Links: Espacenet, EP Register
Gasket for automotive engine transmission
EP 0592691 A1
Abstract
A gasket for automotive engine transmission, made from a cross-linking composition comprising 100 parts by weight of a polymer prepared by dissolving or swelling a noncrystalline fluoropolymer in an acrylic monomer and polymerizing the monomer, 0.1 to 100 parts by weight of a filler, and 0.1 to 10 parts by weight of a cross-linking agent. This gasket is excellent in mechanical strength and resistance to engine oil bubbling at high temperatures and also in compression set, resistances to automatic transmission fluid and long-life coolant, and durability.
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Claims(8)
  1. A gasket for motor vehicle engines and transmissions which is prepared from a crosslinkable composition comprising 100 parts by weight of a polymer, 0.1 to 100 parts by weight of a filler and 0.1 to 10 parts by weight of a crosslinking agent, the polymer being obtained by dissolving or swelling an amorphous fluorine-containing polymer in an acrylic monomer and subsequently polymerizing the monomer into a high polymer.
  2. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein the amorphous fluorine-containing polymer is vinylidene fluoride/hexafluoropropylene, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene, vinylidene fluoride/chlorotrifluoroethylene and like vinylidene fluoride copolymer, tetrafluoroethylene/propylene, hexafluoropropylene/ethylene and fluoro(alkyl vinyl ether)(including those having a multiplicity of ether bonds)/olefin copolymer, fluorosilicone rubber or fluorophosphazene rubber.
  3. A gasket for motor vehicle engines and transmissions as defined in claim 2 wherein the amorphous fluorine-containing polymer is vinylidene fluoride/hexafluoropropylene, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene or vinylidene fluoride/chlorotrifluoroethylene copolymer.
  4. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein, as the acrylic monomer, the monofunctional acrylic monomer and the polyfunctional acrylic monomer are used conjointly.
  5. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein the polyfunctional monomer is used in an amount of 1 to 20 parts by weight per 100 parts by weight of the monofunctional monomer.
  6. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein the acrylic monomer is used in an amount of 5 to 1000 parts by weight per 100 parts of the amorphous fluorine-containing polymer.
  7. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein the filler is carbon black, silica, clay, kieselguhr, talc or calcium carbonate.
  8. A gasket for motor vehicle engines and transmissions as defined in claim 1 wherein the crosslinking agent is peroxide, polyol or polyamine.
Description
    (Technical field)
  • [0001]
    The present invention relates to gaskets for motor vehicle engines and transmissions.
  • (Background art)
  • [0002]
    Gaskets for motor vehicles are used for sealing off the covers to be attached to the cylinder heads of motor vehicle internal combustion engines, and can be checked for suitability including that of the material thereof when subjected to thermal loads and vibrations during operation. More specifically, they must be resistant to cold for starting engines in a cold state and resistant to heat under high-speed loads. If the engine oil or transmission oil leaks owing to a temperature difference between the intake side and the exhaust side of the engine or to the angle at which the engine is mounted on the vehicle, the oil will drip onto the exhaust pipe in view of the construction of the engine, so that the gasketed portion is exposed to a great fire hazard.
  • [0003]
    While such gaskets for motor vehicle engines and transmissions have heretofore been prepared from an acrylic elastomer or fluorine-containing polymer, the former has the drawback of being inferior in heat resistance, mechanical strength when hot and resistance to engine oil bubbling. Although the latter is satisfactory in heat resistance and resistance to engine oil bubbling, the material has the drawback of being very low in mechanical strength when hot.
  • [0004]
    Accordingly, we prepared gaskets for motor vehicle engines and transmissions from a blend of both acrylic elastomer and fluorine-containing polymer. Unexpectedly, however, we found that the gaskets were seriously inferior in all the properties of heat resistance, mechanical strength when hot and resistance to engine oil bubbling. This is apparent from the comparative example given later.
  • [0005]
    An object of the present invention is to provide a gasket for motor vehicle engines and transmissions which is made of a vulcanized rubber prepared from a homogeneous dispersion of fluorine-containing polymer and acrylic elastomer and not undergoing phase separation, the gasket having outstanding heat resistance, mechanical strength when hot and resistance to engine oil bubbling as characteristics imparted thereto by the respective materials.
  • [0006]
    Another object of the invention is to provide a gasket for motor vehicle engines and transmissions which is excellent also in compression set (CS), resistance to ATF (Automatic Transmission Fuel), resistance to LLC (Long Life Coolant) and durability.
  • [0007]
    The present invention provides a gasket for motor vehicle engines and transmissions which is prepared from a crosslinkable composition comprising 100 parts by weight of a polymer, 0.1 to 100 parts by weight of a filler and 0.1 to 10 parts by weight of a crosslinking agent, the polymer being obtained by dissolving or swelling an amorphous fluorine-containing polymer in an acrylic monomer and subsequently polymerizing the monomer into a high polymer.
  • [0008]
    We have conducted intensive research in order to prepare homogeneous dispersions from fluorine-containing polymers and acrylic elastomers and to cause the two comonents to retain compatibility with each other after a heat treatment for vulcanization, and consequently prepared a gasket for use in motor vehicle engines and transmissions from a crosslinkable composition which is obtained by dissolving or swelling a fluorine-containing polymer in an acrylic monomer, thereafter polymerizing the acrylic monomer to prepare a polymer and admixing a filler and a crosslinking agent with the polymer. We have found that the gasket has outstanding properties in respect of heat resistance, mechanical strength in a hot state and resistance to engine oil bubbling which properties are unexpectable from mere blends of fluorine-containing polymers and acrylic elastomers as kneaded together.
  • [0009]
    The gasket of the invention for motor vehicle engines and transmissions is excellent also in compression set, ATF resistance, LLC resistance and durability.
  • [0010]
    Examples of amorphous fluorine-containing polymers which can be dissolved or swollen in acrylic monomers for use in the present invention are vinylidene fluoride/hexafluoropropylene, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene, vinylidene fluoride/chlorotrifluoroethylene and like vinylidene fluoride copolymers, tetrafluoroethylene/propylene, hexafluoropropylene/ethylene and fluoro(alkyl vinyl ether) (including those having a multiplicity of ether bonds)/olefin copolymers, fluorosilicone rubber, fluorophosphazene rubber, etc. Preferable among these are vinylidene fluoride/hexafluoropropylene, vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene and vinylidene fluoride/chlorotrifluoroethylene polymers.
  • [0011]
    The term "amorphous" as used herein refers to elastomers the melting point of which is not observable substantially at the peak of DSC (Differential Scanning Colorimeter).
  • [0012]
    Acrylic monomers for use in the present invention are not limited and include mono- and poly- functional monomers. Such monomers are used singly, or at least two of them are used in combination. Preferably, polyfunctional monomers are used in a small amount in combination with a monofunctional monomer. Examples of preferred monomers are methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), 2-hydroxyethyl methacrylate (HEMA), glycidyl methacrylate (GMA), 2-methoxyethyl methacrylate (MEMA), 3-(trimethoxysilyl)propyl methacrylate (MSPM), 2-(phenylphosphoryl)ethyl methacrylate (phenyl-P), 2-hydroxy-3-(β-napthoxy)propyl methacrylate (HNPM), N-phenyl-N-(2-hydroxy-3-methacryloxy)propylglycine (NPG-GMA), ethylene glycol dimethacrylate (EDMA or 1G), diethylene glycol dimethacrylate (DiEDMA or 2G), triethylene glycol dimethacrylate (TriEDMA or 3G), tetraethylene glycol dimethacrylate (TEDMA or 4G), 1,4-butanediol dimethacrylate (1,4-BuDMA), 1,3-butanediol dimethacrylate(1,3-BuDMA), 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (Bis-GMA), 2,2-bis(4-methacryloxyphenyl)propane (BPDMA), 2,2-bis(4-methacryloxyethoxyphenyl)propane (Bis-MEPP), 2,2-bis(4-methacryloxypolyethoxyphenyl)propane (Bis-MPEPP), di(methacryloxyethyl)trimethylhexamethylenediurethane (UDMA), trimethylolpropanetrimethacrylate (TMPT),
    CH₂ = C(CH₃)COOCH₂CF₃ (3FMA),
    CH₂ = C(CH₃)COOCH₂CF₂CF₂H (4FMA),
    CH₂ = C(CH₃)COOCH₂CF₂CF₃ (5FMA),
    CH₂ = C(CH₃)COOCH₂(CF₂)₂CF₃ (7FMA),
    CH₂ = C(CH₃)COOCH₂(CF₂)₃CF₂H (8FMA),
    acrylates and α - fluoroacrylates corresponding to such compounds.
  • [0013]
    Examples of α -fluoroacrylates are
    CH₂ = CFCOOCH₂CF₂CF₂H (4FFA),
    CH₂ = CFCOOCH₂CF₂CF₃ (5FFA),
    CH₂ = CFCOOCH₂(CF₂)₃CF₂H (8FFA) and
    CH₂ = CFCOOCH₂(CF₂)₅CF₂H (12FFA).
  • [0014]
    To modify the monomer, the monomer may have admixed therewith a small amount of acrylonitrile, 2-chloroethyl vinyl ether, vinyl monochloroacetate, methylvinyldichlorosilane or the like. When the polyfunctional monomer is to be used, it is suitable to use the polyfunctional monomer in an amount of 1 to 20 parts (by weight, the same as hereinafter) per 100 parts by weight of the monofunctional monomer.
  • [0015]
    The proportions of the amorphous fluorine-containing polymer and the acrylic monomer to be used in the present invention can be determined suitably. It is generally desirable to use 5 to 1000 parts of the latter per 100 parts of the former.
  • [0016]
    According to the present invention, the fluorine-containing polymer is dissolved or swollen in the acrylic monomer, which is then polymerized into a high polymer. The polymerization is conducted in the presence of a polymerization initiator. A polymerization inhibitor, reducing agent, transfer agent, etc. can be added to the polymerization system. Examples of useful polymerization initiators are light, heat, benzoyl peroxide, azoisobutyronitrile (AIBN), camphorquinone (CQ), 9-fluorenone, tributylborane (TBB), benzophenone and the like. Examples of useful reducing agents are dimethylaminoethyl methacrylate (DMAEMA), dimethyl-p-toluidine (DMPT) and the like. Examples of useful polymerization inhibitors are hydroquinone, hydroquinone methyl ester and the like. Examples of useful transfer agents include lauryl mercaptan.
  • [0017]
    Cross linking of the composition of the invention or use of the polyfunctional acrylic monomer forms an IPN (interpenetrating polymer network). IPN is a polymer obtained by mixing two linear polymers together each in the form of a liquid (or solution) and crosslinking one or both of the polymers to interlock the respective molecular chains. When IPN is to be formed according to the invention, the following method is usually employed. A monomer for forming a guest polymer is injected into the high polymer formed. Alternatively, the polymer is immersed in or injected into a solution containing the monomer. The mixture is then polymerized by heating, irradiation with light or like procedure, a filler, crosslinking agent, etc. are admixed with the resulting polymer, and the mixture is crosslinked. Other methods are also usable.
  • [0018]
    Examples of fillers useful for the present invention are carbon black, silica, clay, kieselguhr, talc, calcium carbonate and like reinforcing agents. The filler is used preferably in an amount of 0.1 to 100 parts per 100 parts of the polymer. If the amount is less than 0.1 part, an insufficient reinforcing effect will result, whereas if the amount is over 100 parts, the composition fails to exhibit rubberlike properties.
  • [0019]
    Examples of crosslinking agents useful for the invention are those for use in crosslinking vinylidene fluoride-containing rubbers, such as peroxides, polyols and polyamines. More specific examples are Perhexa 2.5B (peroxide manufactured by Nippon Oils & Fats Co., Ltd.), triallyl isocyanurate (TAIC) bisphenol AF, N,N'-dicinnamylidene-1,6-hexadiamine, etc. The crosslinking agent is used preferably in an amount of 0.1 to 10 parts per 100 parts of the polymer. If the amount is less than 0.1 part, the degree of crosslinking achieved is insufficient, whereas if the amount is in excess of 10 parts, the composition is unlikely to exhibit rubberlike properties.
  • [0020]
    When required, also usable are nitrogen- or phosphorus- containing organic tertiary or quaternary compounds as crosslinking accelerators, oxides or hydroxides of bivalent metals as an acid-acceptor, and compounds containing a plurality of vinyl or allyl groups and serving as auxiliary crosslinking agents. Further usable as required are antioxidants, processing assisting agents, scorch retarders, antiozonants, ultraviolet absorbers, flame retardants, plasticizers and other additives.
  • [0021]
    The gasket for motor vehicle engines and transmissions which is obtained according to the invention by dissolving or swelling the fluorine-containing polymer in the acrylic monomer and subsequently polymerizing the monomer is unexpectedly exceedingly superior in heat resistance, mechanical strength when hot and resistance to engine oil bubbling to those obtained from a mere blend of fluorine-containing polymer and acrylic elastomer.
  • [0022]
    The gasket of the invention for motor vehicle engines and transmissions is excellent also in compression set, ATF resistance, LLC resistance and durability.
  • [0023]
    The composition of the invention has a slightly higher viscosity than usual simple blended rubber materials, so that when comprising a peroxide which is decomposable at a low temperature (50 to 130 C ) and a polyfunctional compound (as cross linking agents), the composition is applicable in situ for providing gaskets and can be vulcanized by being subjected to a hot-air atmosphere of 60 to 150 C .
  • (Best mode of carrying out the invention)
  • [0024]
    Examples and Comparative Examples are given below. In these examples, the parts and percentages are all by weight.
  • Example 1 and Comparative Examples 1 to 3
  • [0025]
    Gaskets for motor vehicles were prepared from compositions comprising components listed in Table 1 below.
  • Comparative Example 4
  • [0026]
    Gaskets for motor vehicles were prepared in the same manner as in Example 1 from a composition obtained by blending the compositions of Comparative Examples 2 and 3 in the ratio of 50 : 50 by weight.
    In table 1 :
    G702 : vinylidene fluoride/hexafluoropropylene copolymer, product of Daikin Industries, Ltd.
    FAU-014Y: copolymer of G702/nBuAc/1,6-HXA(70/27/3)
    nBuAc : n-Butyl acrylate
    1,6-HXA : 1,6-Hexanediol diacrylate
    Naugard 445 : Age resistor, product of Uniroyal Chemical Co., Ltd. Table 1
    Example 1 Comparative Example
    1 2 3 4
    Halogen-containing acrylic rubber - 100 100 - 30
    G 702 - - - 100 70
    FAU-014Y 100 - - - -
    Stearic acid - 1 1 - 1
    MgO - - - 6.0 4.2
    HAF Carbon - 65 60 - 65
    MT Carbon 20 - - 20 -
    Plasticizer - - 5 - -
    Sulfur - 0.3 - - -
    Potassium stearate - 0.5 - - -
    Sodium stearate - 3.0 - - -
    Zinc-di-n-butylthiocarbamate - - 1.5 - 0.5
    2,4,6-Trimercapto-S-triazine - - 0.5 - 0.2
    Ca(OH)₂ - - - 3.0 2.1
    2,5-dimethyl-2,5-di-(t-butylperoxy)hexane 1.5 - - - -
    Triallyl isocyanurate 4 - - - -
    Naugard 445 0.6 - - - -
  • [0027]
    The properties of the foregoing compositions were evaluated by the following methods. Table 2 shows the results.
    • (1) Tensile strength (T b) : According to JIS 6301.
    • (2) Tear strength (T R) : According to JIS 6301.
    • (3) Compression set (CS) : According to JIS 6301.
    • (4) German low temperature-torsional test : Measured according to JIS 6301 using refrigerant isopropyl alcohol (IPA).
    • (5) Resistance to engine oil bubbling : Measured using Nissan Extra Save X (7.5W-30), 150C 72hr
    • (6) ATF resistance : 150C 72hr, Castle fluid Dexron 2
    • (7) LLC resistance 120C 48hr, Toyota genuine LLC and water (1:1 vol ratio)
    • (8) Heat resistance : 175C 500hr
    • (9) Durability : The gasket tested was 5 9mm in cross section and having a cover groove measuring 5 6mm.
      • (a) Initial assembling bearing pressure : At least 30kgf/cm, 30 % compression.
      • (b) Initial sealing property : At least 2 kgf/cm in bearing pressure, 30 % compression.
      • (c) Crack resistance : 6 mm in groove depth, 9 mm in height, 3 mm in exposed part, 50 % compression, 150C 24hr, 5 cycles.
      • (d) Continuous high-speed endurance : 30 % compression, 150C 500hr
      • (e) Thermal shock leak endurance : 30 % compression, (150C 15hr) + (-30C 9hr), 20 cycles, filled with oil and free of pressure, was subjected to thermal shock, and checked for leakage with reference to a color change in micro-check indicating oozing oil.
  • (Industrial applicability)
  • [0028]
    The gasket of the invention for motor vehicle engines and transmissions has outstanding heat resistance, mechanical strength when hot and resistance to engine oil bubbling. Further, the gasket of the invention for motor vehicle engines and transmissions is excellent in compression set, ATF resistance, LLC resistance and durability.
Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
EP0385443A2 *Feb 28, 1990Sep 5, 1990Daikin Industries, LimitedPolymer material having shape memory characteristics
EP0481372A2 *Oct 11, 1991Apr 22, 1992Daikin Industries, LimitedCrosslinkable composition
Non-Patent Citations
Reference
1 *See also references of WO9322586A1
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
EP0857757A1 *Feb 6, 1998Aug 12, 1998Ausimont S.p.A.Blends of fluorinated and acrylic elastomers
US5902860 *Feb 10, 1998May 11, 1999Ausimont S.P.A.Blends of fluorinated and acrylic elastomers
Classifications
International ClassificationC08K5/00, C08L33/06, C08K3/00, C08L27/12
Cooperative ClassificationC08K3/013, C08L27/12, C08L2205/04, C08L33/06, C08K5/0025
European ClassificationC08L33/06, C08L27/12, C08K3/00P5, C08K5/00P2
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